FIG. 1 is a schematic diagram illustrating a user interacting with a conventional 3D image interactive system. As depicted in FIG. 1, a real user 15 interacts with a conventional 3D image interactive system (such as a 3D video game system) 10. The 3D image interactive system 10 mainly includes a display-and-interactive device 12 configured for generating a 3D image. In the 3D display technology, it is understood that the real user 15 has to wear a 3D glasses (not shown) to watch the 3D image displayed by the display-and-interactive device 12.
As depicted in FIG. 1, the real user 15 can only interact with the 3D image interactive system 10 via a virtual user 14 which is generated by the display-and-interactive device 12. In other words, the real user 15 does not directly interact with the 3D image interactive system 10, instead, the real user 15 interacts with the 3D image interactive system 10 via a virtual user 14, which is controlled by a remote controller (or other positioning device) 16 hold by the real user 15. Because the real user 15 does not directly interact with the 3D image interactive system 10, the real user 15 may not feel so real.
To make a user have a better immersive experience, most of the modern 3D image interactive systems are equipped with a detecting device which is for detecting a user's action, and the modern 3D image interactive systems can immediately perform a response action in response to the user's action, so that a direct interaction between the user and the 3D image interactive systems is realized. FIG. 2 is a schematic diagram illustrating a user interacting with a modern 3D image interactive system. As depicted in FIG. 2, the modern 3D image interactive system 20 mainly includes a display-and-interactive device 22 and a detecting device 24; wherein the detecting device 24 is coupled via signal to the display-and-interactive device 22. Additionally, most of the modern 3D image interactive systems have a predefined default position, and a good interaction can be achieved when the user is always at the default position to interact with the 3D image interactive systems. Please refer to FIG. 2, the default position of the 3D image interactive system 20 is set at P(X0, Y0, Z0) in an interactive coordinate system 26 which is defined in front of the display-and-interactive device 22; wherein Z0 is the distance between the default position P(X0, Y0, Z0) and the display-and-interactive device 22. When the user is positioned at the default position P(X0, Y0, Z0) and interacts with the 3D image interactive system 20, the detecting device 24 keeps detecting the user's action and the 3D image interactive system 20 performs a response action based on the user's action at the default position P(X0, Y0, Z0), so that the direct interaction of the user to the 3D image interactive system 20 is realized.
In the 3D display technology, it is understood that even though the user is not at the default position, the user can still observe an almost same 3D image. For example, please refer to FIG. 2, whether the user is positioned at P(X0, Y0, Z0) or Q(X1, Y1, Z1), he or she can observe at a same specific time a 3D image generated by the 3D image interactive system 20, except that the 3D image observed at Q(X1, Y1, Z1) may have a shear distortion comparing with the 3D image observed at P(X0, Y0, Z0). However, when the user is positioned at Q(X1, Y1, Z1) to interact with the 3D image interactive system 20, the 3D image interactive system 20 would not work normally, because the 3D image interactive system 20 can produce a response action only based on the user's action at the default position P(X0, Y0, Z0).